If Kupp, or Puka, or even Tutu went down or if we went crazy-empty backfield, I'd want guys with hands, who could catch in traffic, and could block - as the two remaining starters would likely get most of the targets.
Skow and Robinson fill all those criteria; Trammel might but I don't know about his blocking. He plays faster than his 4.6 forty time, is elusive and shifty in traffic. Enter Skow, Robby, and Trammel.
I wouldn't want a guy who was questionable in traffic, whose hands were not always dependable, whose speed made him a potential deep threat but who nullified that potential because he couldn't consistently track the ball and time the catch well, who hit his ceiling and whose heart wasn't in it. Exit Van.